| BackgroundRecurrent implantation failure(RIF)means that women under 40 years old transfer at least 4 high-quality embryos in at least three in vitro fertilization-embryo transfer cycles without getting pregnant,which is one of the difficult problems affecting the success rate of human assisted reproductive technology.Studies have shown that one of the main factors of RIF caused by poor endometrial receptivity,the mechanism is not clear.Therefore,the study of endometrial receptivity is an important link in the prevention and treatment of embryo implantation failure.So far,the evaluation of endometrial receptivity mainly depends on endometrial thickness,type,uterine artery and subendometrial blood flow parameters,but the value of these methods is limited.As a new non-invasive method for evaluating endometrial receptivity,secretomics has been widely used in the field of human reproduction,and many proteins have been identified,which may be potential biomarkers or therapeutic targets for successful pregnancy in human assisted reproductive techniques.Proprotein convertase 6(PC6)is a secretory protein,which belongs to the PC family.After translation,it can activate a variety of precursor proteins related to decidualization of endometrial stromal cells and embryo implantation,such as bone morphogenetic protein 2,platelet-derived growth factor,ezrin-radixin-moesin binding phosphoprotein-50 and so on.Studies have shown that PC6 is the only proprotein convertase that is highly regulated in the endometrium and is associated with receptivity and implantation.However,there is no study on the expression of PC6 in the endometrium of patients with RIF.ObjectiveThe uterine lavage fluid and endometrial tissue samples of patients with RIF and IVF pregnancy were selected to explore whether PC6 could be detected in uterine lavage fluid,and to analyze the changes of PC6 expression in uterine lavage fluid and endometrial tissue of the two groups.Methods1.Collection of uterine lavage fluid and endometrial tissue:1)time:uterine lavage fluid and endometrium of patients with RIF and IVF pregnancy were collected during 20-24 days of the natural menstrual cycle before IVF assisted pregnancy;2)uterine lavage fluid collection method:5ml aseptic saline was gently injected into the uterine cavity by a soft artificial insemination catheter,and then the fluid was recovered by aspiration;3)endometrial collection method:aspiration of endometrial tissue through an endometrial stimulation tube.2.The treatment of uterine lavage fluid:centrifuge(235g/5min)to remove cell fragments,absorb the supernatant and put it into a frozen tube,and immediately cryopreservation in the refrigerator at-80℃.3.The method of endometrial tissue treatment:rinse clean with phosphate buffer saline,remove excess water,and directly freeze in a liquid nitrogen tank to be tested.Results1.Expression of PC6 in uterine lavage fluid:The results of ELISA showed that there was PC6 in uterine lavage fluid,and the secretion level of PC6 in patients with RIF was significantly lower than that in patients with IVF pregnancy.2.The expression of PC6 in endometrium:1)the results of qRT-PCR showed that PC6mRNA could be detected in endometrial tissues of RIF and IVF pregnant patients.Compared with IVF pregnant women,PC6mRNA expression was significantly down-regulated in the endometrial tissues of RIF(*p<0.05).2)Western blot analysis showed that PC6 protein could be detected in endometrial tissues of RIF patients and IVF pregnant patients.The expression of PC6 protein in the endometrium of RIF patients during mid-secretory period was significantly lower than that of IVF pregnant patients(***p<0.001).Conclusion1.PC6 can be obtained by noninvasive uterine lavage.2.The PC6 level in uterine lavage fluid of patients with recurrent implantation failure was significantly lower than that of IVF pregnant patients.3.Compared with IVF pregnant patients,the expression of PC6 in the endometrial tissue of patients with recurrent implantation failure was significantly down-regulated. |
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